The present invention relates to an electronic lottery system composed of a server and a plurality of terminals, which electronically draw lots.
Many conventional systems using mechanical methods to draw lots have previously been proposed, described as follows:
Laid-open Hei7-131533 (hereafter, referred to as reference 1) shows the xe2x80x9cLottery application reception systemxe2x80x9d, in which telephones are utilized in the operation of a lottery in such a way that the server accepts lottery applications via the push-tone signals or acoustic signals sent by telephone from the terminals.
Laid-open Hei8-101872 (hereafter, referred to as reference 2) shows the xe2x80x9cFacility reservation management systemxe2x80x9d, in which the server accepts the reservation of a facility sent from a terminal, and draws lots when reservations conflict, and then notifies the result of the lot drawing to the terminals.
Laid-open Hei7-287731 (hereafter, referred to as reference 3) shows the xe2x80x9cNetwork-type card lottery management apparatus and central card lottery management methodxe2x80x9d, in which a central data management apparatus in the server accepts lottery applications using lottery cards from a terminal data management apparatus in the terminals and then draws lots, and then notifies the results to the terminals.
Laid-open Sho61-18085 (hereafter, referred to as reference 4) shows the xe2x80x9cPublic lottery apparatusxe2x80x9d, located in the terminal, which issues a public lottery ticket with a public lottery number that a person wants.
Laid-open Hei1-319896 (hereafter, referred to as reference 5) shows the xe2x80x9cElectronic cash register with a lottery functionxe2x80x9d, which draws lots by generating a random number when its sum-up key is pushed, and then determines whether this number matches a prize number previously stored in its memory.
Laid-open Hei5-124305 (hereafter, referred to as reference 6) shows the xe2x80x9cPrint-out processing methodxe2x80x9d of increasing a lottery""s drama by hiding the result of an Amitabha-type lottery in such a way that it suspends the print-out when an Amitabha-type lottery drawing is printed out and then resumes the operation.
Laid-open Hei6-96109 (hereafter, referred to as reference 7) shows the xe2x80x9cgame apparatusxe2x80x9d, which provides a resultant lottery by electronically generating an Amitabha-type pattern with several long lines along which include short lines bridged between the long lines, and displaying them, and then selecting one of the long lines according to people""s requests.
As described above, there are many conventional proposals for using mechanical methods to draw lots. However, these methods have the objective of automating the reception of applications to enter the lottery and then the drawing of lots. Impartiality, which is a most important factor in a lottery, is not sufficiently taken into account. For instance, in references 1 and 2, the server draws lots, but does so without assuring that the lottery operation is impartially performed. In reference 3, the lottery is performed in accordance with a recorded number on a card; however, this system is vulnerable to unfair acts such as an act of altering the number recorded on the card. The use of the method detailed in reference 4 can prevent the lottery numbers from being altered since they are printed on public lottery tickets, but there is no guarantee of an impartial lottery being made by the server. In the method detailed in reference 5, the fact that a random number is generated cannot prevent the possibility of unfair acts being made because a prize number which has previously been stored in the memory can be altered. In the methods detailed in references 6 and 7, the act of drawing lots is accomplished using an Amitabha-type lottery pattern which is selected by the apparatus. The pattern can be easily altered after lottery applications are accepted, thus resulting in a profitable result for a certain person.
As described above, using the server to determine the lottery result creates the possibility that unfair operations will lead to a specific lottery result being made. When the result of drawing lots is determined before terminals participate, there is the possibility that one or more of the terminals can cheat.
The objective of the present invention is to provide an electronic lottery method and system, by which a lottery result is obtained in accordance with random numbers selected by a server and a plurality of terminals. None of subsystems can cheat the lottery result. Another objective of the present invention is to provide a computer-readable recording medium, on which an electronic lottery program code is recorded, and by which the electronic lottery operations are performed.
In accordance with a first embodiment of the invention, a server generates a random number x, determines other settings such as a result function R and an encrypting function H, encrypts the random number x using the encrypting function H to produce an encrypted random number H(x), and publishes the encrypting function H, the result function R, and the encrypted random number H(x). Terminals then obtain the published encrypting function H, result function R, and encrypted random number H(x), and then generate respective random numbers ri and send those random numbers ri to the server. The server verifies each received random number ri using a signature of the terminal, normalizes the random numbers ri, and calculates a lottery result R(x, r) using the random number x generated by the server and the random numbers ri generated by the terminals. The server then publishes the lottery result R(x, r), each random number ri provided by the terminals, and the random number x generated by the server. These values are obtained by each terminal, and each terminal verifies the correctness of its own random number ri, verifies the published random number x using the encrypting function H and the encrypted random number H(x), and verifies the lottery result R(x, r) using the result function R, the server random number x, and the terminal random numbers ri.
In accordance with a second embodiment of the invention, a server generates a random number x, determines other settings such as a result function R and an encrypting function H, encrypts the random number x using the encrypting function H to produce an encrypted random number H(x), and publishes the encrypting function H, the result function R, and the encrypted random number H(x). Terminals then obtain the published encrypting function H, result function R, and encrypted random number H(x). The terminals then generate respective random numbers yj, encrypt those random numbers using the encrypting function H to generate encrypted random numbers H(yj), and send those encrypted random numbers H(yj) to the server. The server verifies each received encrypted random number H(yj) using a signature of the terminal, and publishes all encrypted random numbers H(yj). Each terminal then obtains all published encrypted random numbers H(yj), verifies that all encrypted random numbers H(yj) of terminals in the lottery have been obtained, verifies that its own published encrypted random number H(yj) is correct, and if it is correct, sends its own random number yj to the server. The server receives the random numbers yj, verifies each random number yj using a signature of the corresponding terminal, verifies the value of each random number yj using the corresponding encrypted random number H(yj) and the encrypting function H, normalizes the random numbers yj, and calculates a lottery result R(x, y) using the random number x generated by the server and the random numbers yj generated by the terminals. The server then publishes the lottery result R(x, y), each random number yj provided by the terminals, and the random number x generated by the server. These values are obtained by each terminal, and each terminal verifies the correctness of its own random number yj, verifies the published random number x using the encrypting function H and the encrypted random number H(x), verifies all random numbers yj using the encrypting function H and the encrypted random numbers H(yj), and verifies the lottery result R(x, y) using the result function R, the server random number x, and the terminal random numbers yj.
A third embodiment comprises first terminals of the type described with respect to the first embodiment, and further comprises second terminals of the type described with respect to the second embodiment. In the third embodiment, the result generation function R determines a result R(x, r, y) using a random number x generated by the server, random numbers ri generated by the first terminals, and random numbers yj generated by the second terminals. The processing in the terminals allows each terminal to verify the encrypted random numbers supplied by the second terminals.
In the third embodiment, a server generates a random number x, determines other settings such as a result function R and an encrypting function H, encrypts the random number x using the encrypting function H to produce an encrypted random number H(x), and publishes the encrypting function H, the result function R, and the encrypted random number H(x). First terminals (i) as described in the first embodiment obtain the published encrypting function H, result function R, and encrypted random number H(x), then generate respective random numbers ri, and send those random numbers ri to the server. The server receives the random numbers ri, and verifies each received random number ri using a signature of the terminal.
Concurrently, second terminals (j) as described in the second embodiment obtain the published encrypting function H, result function R, and encrypted random number H(x). The second terminals then generate respective random numbers yj, encrypt those random numbers using the encrypting function H to generate encrypted random numbers H(yj), and send those encrypted random numbers H(yj) to the server. The server receives each encrypted random numbers H(yj), and verifies each received encrypted random number H(yj) using a signature of the terminal.
The server then verifies that all random numbers ri and all encrypted random numbers H(yj) have been received from the respective terminals, and publishes all random numbers ri and all encrypted random numbers H(yj).
The first terminals (i) obtain all published random number ri and encrypted random numbers H(yj), verify that the random numbers ri and encrypted random numbers H(yj) of all terminals have been received, and verify that their own random number ri is published correctly. Concurrently, the second terminals (j) obtain all published random number ri and encrypted random numbers H(yj), verify that the random numbers ri and encrypted random numbers H(yj) of all terminals have been received, and verify that their own encrypted random number H(yj) is published correctly, and if published correctly, send their random number yj to the server.
The server receives the random numbers yj, verifies each random number yj using a signature of the corresponding terminal, verifies the value of each random number yj using the corresponding encrypted random number H(yj) and the encrypting function H, normalizes the random numbers ri and yj, and calculates a lottery result R(x, r, y) using the random number x generated by the server and the random numbers ri and yj generated by the terminals. The server then publishes the lottery result R(x, r, y), each random number ri and yj provided by the terminals, and the random number x generated by the server.
The published values are obtained by the first terminals (i), and each terminal verifies the correctness of its own random number ri, verifies the published random number x using the encrypting function H and the encrypted random number H(x), verifies that all random numbers yj of the second terminals are correct using the encrypting function H and the encrypted random numbers H(yj), and verifies the lottery result R(x, r, y) using the result function R, the server random number x, and the terminal random numbers ri and yj. Concurrently, the published values are obtained by the second terminals (j), and each terminal verifies the correctness of its own random number yj, verifies the published random number x using the encrypting function H and the encrypted random number H(x), verifies that all random numbers yj of the second terminals are correct using the encrypting function H and the encrypted random numbers H(yj), and verifies the lottery result R(x, r, y) using the result function R, the server random number x, and the terminal random numbers ri and yj.
In each of the embodiments, the server may use a hash function, such as the MD5 or the RIPE-MD, to encrypt the random numbers and also to obtain the lottery result. The terminals can also use such functions to encrypt their random numbers.
The invention may be embodied in methods, programmed machines, and computer readable media storing programming instructions.